Kobold NWS Operating Instructions Manual
Operating Instructions
for
Level Switch
Tuning Fork Principal
Model: NWS
NWS
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1. Contents
1. Contents ........................................................................................................ 2
2. Note .............................................................................................................. 3
3. Instrument Inspection .................................................................................... 3
4. Regulation Use .............................................................................................. 3
5. Operating Principle ........................................................................................ 4
6. Use in Hazardous Areas (NWS-2E) .............................................................. 4
6.1 Device function .................................................................................... 4
6.2 Commissioning/Installation .................................................................. 5
6.3 Designation .......................................................................................... 5
6.4 Temperature resistance ....................................................................... 6
7. Mechanical Connection ................................................................................. 6
8. Electrical Connection .................................................................................... 7
8.1 NWS-...200 .......................................................................................... 7
8.2 NWS-...23/24; NWS-...2W/2H; NWS-...2E (ATEX certification) ........... 9
9. Settings ....................................................................................................... 10
9.1 Settings for NWS-...200.. ................................................................... 10
9.2 Settings for NWS-...23/24/2W/2H and NWS-2E ................................ 12
10.Technical Information .................................................................................. 15
11.Order Codes ............................................................................................... 17
12.Service and Maintenance ............................................................................ 17
13.Trouble Shooting ......................................................................................... 17
14.Recommended Spare Parts ........................................................................ 18
15.Disposal ...................................................................................................... 18
16.Dimensions ................................................................................................. 19
17.Declaration of Conformance ....................................................................... 21
18.Supplement to the EC-Type Examination certificate ................................... 22
19.IECEx Certificate ......................................................................................... 25
Manufactured and sold by:
Kobold Messring GmbH
Nordring 22-24
D-65719 Hofheim/Germany
Tel.: +49(0)6192-2990
Fax: +49(0)6192-23398
E-mail: info.de@kobold.com
Internet: www.kobold.com
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2. Note
Please read these operating instructions before unpacking and putting the unit
into operation. Follow the instructions precisely as described herein.
The devices are only to be used, maintained and serviced by persons familiar
with these operating instructions and in accordance with local regulations
applying to Health & Safety and prevention of accidents.
When used in machines, the measuring unit should be used only when the
machines fulfil the EWG-machine guidelines.
3. Instrument Inspection
Instruments are inspected before shipping and sent out in perfect condition.
Should damage to a device be visible, we recommend a thorough inspection of
the delivery packaging. In case of damage, please inform your parcel service /
forwarding agent immediately, since they are responsible for damages during
transit.
Scope of delivery:
The standard delivery includes:
Level Switch model: NWS
Operating instructions
4. Regulation Use
Kobold model NWS Liquid-Level Switches are designed to be wired as 2-wire or
3-wire switches and can be universally installed in any position in containers and
piping. They can be used in many types of liquids including oils, water, paints and
varnishes, sauces, milk, carbonated liquids and foamy oils. The liquid may have a
maximum viscosity of 5000 cSt. At higher viscosities, the response time may
increase. NWS Liquid-Level Switches are ideally suited for use in hygienic and
sterile applications and designed to withstand CIP cleaning methods at temperatures up to 150 °C.
Any use of the device which exceeds the manufacturer’s specification may
invalidate its warranty. Therefore any resulting damage is not the responsibility of
the manufacturer. The user assumes all risk for such usage.
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5. Operating Principle
The KOBOLD liquid level switch NWS is designed as a 2 and 3-wire switch and
can be universally used in vessels and pipelines. The NWS operates on the
tuning fork principle in air at resonance frequency. A piezoelectric crystal is used
for excitation of oscillations and for monitoring the actual oscillation frequency.
When the fork is immersed in liquid, the frequency changes: this change is
detected electronically and the output signal is changed. The NWS operates as a
two-wire switch in series with the load. The simple electronic switch is operated
by the liquid. The NWS can also be connected to a PLC through a third terminal.
Special Features:
The NWS has a switch status indicator with LED, which can be seen continuously
through a lens in the cover. The LED flashes approximately once every second,
when the NWS has switched off and goes onto a permanent light, when the NWS
is switched on. The LED is a visible confirmation that the NWS is working
correctly and that the condition of the wet side is correctly indicated. With a
selector switch the NWS can be set either as an upper limiter or as a lower
limiter.
6. Use in Hazardous Areas (NWS-2E)
6.1 Device function
The intrinsically safe NAMUR oscillating fork sensor is used to detect the fill
levels of combustible and non-combustible liquids. The sensor is supplied with
current from a switching amplifier with an intrinsically safe output circuit in
accordance with the NAMUR specification and behaves accordingly when the
oscillating fork is dampened by liquid or can oscillate freely. The sensor can be
used in all zones in gaseous hazardous areas.
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6.2 Commissioning/Installation
The devices may be installed in zones 0, 1 and 2. The intrinsically safe
circuits must be installed (by specialists) in conformance with the
applicable installation requirements (certification document of installer,
protected routing of the intrinsically safe circuits, etc.).
The devices are constructed in accordance with protection type IP 65. If
applicable, they must be protected against adverse environmental
conditions.
The EU model test certificates must be complied with. Any “special
regulations” contained in them must be followed.
The device should only be used for its intended use.
The connection with the associated and/or intrinsically safe equipment
must be separately checked.
The sensors must be grounded to discharge accumulated electrostatic
charge.
At an ambient temperature area of - 5 .. + 70 °C the connected electrical
cable may be mechanically moved. Furthermore at an ambient
temperature area of - 20 .. + 70 °C the electrical cable must be mounted in
a fixed and static manner.
The tuning fork should be protected against external hits.
The connection area of the plug connection version and the connection
cable should be protected against electrostatic charges during its use in
zone 0.
The sensors are by default produced with 1.5 m long cable or with a plug.
In this case a Ci of 8 pF should be taken into account, the internal
inductance is negligible.
o For longer cable length an additional Lc value of 0.14 nF m
-1
and LI
value of 0,65 µH m
-1
per each meter of supplied cable should be
considered.
6.3 Designation
Model: NWS***2E* ****
II 1 G Ex ia IIC T6 Ga
BVS 03 ATEX E 119
IECEx BVS 13.0004
Identification number: 0158
Production-No.: SN: E999999 (consecutively numbered)
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6.4 Temperature resistance
The values for ambient temperatures ranging from -20 °C up to the values
indicated in the following table apply to this sensor, depending on the max.
temperature of the oscillating forks in the sensor:
Ambient temperature 70 °C 70 °C
Medium temperature 75 °C 90 °C
Temperature class T6 T5
7. Mechanical Connection
During installation and removal, recognised and applicable engineering practices
and regulations shall be observed. When working on electrical and pneumatic
plants, the special safety requirements shall be observed.
The NWS switch can be installed in containers or piping by screwing it into a
threaded mounting flange or other type of mounting device. The threaded connection must be sealed with Teflon (PTFE) tape. Be sure to turn the switch at the
hexagonal drive; do not install the switch by turning it at the housing.
After installation, the NWS-...200 can be rotated up to 330° to locate the M16
cable connection (supplied with the device) in a suitable position.
If the switch is installed in a horizontal position, the tuning fork gap should be
positioned vertically so that the liquid can drain from it. If the liquid being monitored is of high viscosity, the switch should be installed so that it extends the
maximum distance into the container or piping in order to prevent the thick liquid
from sticking and accumulating between the fork and the container or pipe wall. If
the switch is installed in piping, the tuning fork gap should be positioned so that it
is parallel to the pipe axis.
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8. Electrical Connection
Attention! Be sure that the supply voltage of your system is the
same as that specified on the device nameplate. Make sure that the
electrical supply lines are de-energised when connecting the device!
8.1 NWS-...200
Series wiring with a 2-wire connection
Please note:
The switch must always be operated in series with a load.
The switch must be grounded at terminal 1.
The switch draws a continuous operating current of less than 3.5 mA (even
when it is "off"). For this reason, it cannot be used for loads that do not allow
an “off” current (such as for gas discharge lamps).
The maximum load current for the switch is 500 mA. The user must provide
suitable protective measures to ensure that this load limit is not exceeded.
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Wiring diagram: 2-wire 24-240V
AC/DC
, series load, I
max
≤ 400mA
PLC connection with 3-wire connection
Please note:
An integral series resistance is used in the 3-wire circuit to generate a
PLC-compliant voltage signal.
The signal can be picked up at terminal 4.
PLC programming devices or computers from various manufacturers will have
different "OFF" threshold voltages. If you should have problems with this setting, please contact us for assistance.
Wiring diagram: 3-wire, VS = 24 VDC,
output PNP: U
HIGH
~ 20 V; U
LOW
~ 3.5 V; I
max
≤ 400 mA
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